LAUSR

The magnetic n–p type Bi2Fe4O9/NiFe2O4 heterostructures with different mass fraction ratios were synthesized by a simple hydrothermal method. A variety of characterization tools involving X-ray diffraction, scanning electron microscope, ultraviolet–visible diffuse reflectance (DRS UV–Vis), fluorescence were applied to analyze the basic characteristics of Bi2Fe4O9/NiFe2O4. The photocatalytic oxidation capacities of Bi2Fe4O9/NiFe2O4 composite were studied through the degradation of methylene blue under UV light. The as-prepared samples exhibited more efficient photocatalytic activities than pure Bi2Fe4O9 and NiFe2O4, which could be attributed to the formation of the n–p junction between n-Bi2Fe4O9 and p-NiFe2O4. Simple magnetic test showed Bi2Fe4O9/NiFe2O4 had good magnetic recovering properties. Continuous photocatalytic experiments demonstrated that the heterojunction structure of Bi2Fe4O9/NiFe2O4 was stable. Based on the results of trapping agents experiments and fluorescence characterization, the catalytic oxidation mechanism of Bi2Fe4O9/NiFe2O4 composite catalysts were further studied, which indicated that ·OH and h+ played critical roles in the process of photocatalytic degradation.